Electrical protector.



UNITED STATES PATENT OFFICE.

CHARLES A. ROLFEpOF CHICAGO, ILLINOIS, ASSIGNOR TO THE ROLFE ELECTRICCOMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

ELECTRICAL PROTECTOR.

SPECIFICATION forming part of Letters Patent No. 724,507, dated April 7,1903.

Application filed June 6, 1900. Serial No. 19,294. @No model.)

To all whom, it may concern:

Be it known that I, CHARLES A. ROLFE, a citizen of the United States,residing at Chicago, in the county of Cook and State of Illi nois, haveinvented a certain new and useful Improvement in Electrical Protectors,(Case No. 2,) of which the following is a full, clear, concise, andexact description, reference being had to the accompanying drawings,forming a part of this specification.

My invention relates to devices for protecting low-tension instrumentsand circuits from the efiects of exceedingly high potentials andexcessively strong currents.

Prominent objects of my invention are to provide an exceedingly simpleand inexpensive protective device for guarding against bothsneak-currents and unduly strong currents and to arrange for theprevention of injurious effects of the discharge of lightning and otherhigh potentials.

To the attainment of the foregoing and other desired ends my inventionconsists in matters hereinafter set forth.

In the accompanying drawings, Figurel is a side elevation of aprotective device embodying my invention. Fig. 2 is a plan view of thesame. Fig. 3 is an end elevation of the device; and Figset and daresections taken on lines 4 4. and 5 5, respectively, in Fig. 2.

The device illustrated in the drawings is provided with an insulatingbase A, which may be of any suitable material, preferably porcelain orslate. This is generally made in two parts 1 and 2, the former being forthat portion of thedevice which is to protect against sneak and undulystrong currents and 1 the latter being for that portion which is toprotect against lightning or like discharges. The two portions of theinsulating-base are desirably mounted upon a strip B, which can be ofany'suitable material. In practice it is generally made of ebonite.'W'hen large nu mbers of the devices are used in one locality, they areall mounted upon a single strip B, which serves as a suitable supportfor them. The base portions 1 and 2 are secured to the strip 13 in anysuitable Way, as by screws 3 4 4. and 4. f.

The portion of the instrumentfor guarding against unduly strong currentscomprises a couple of removable holders C C, which are desirably mountedupon the base portion 1, a simple arrangement being to provide the baseportion with a couple of pairs of spring-contact jaws 5 5 and to providethe holders with blades or shanks 6 6, adapted to slide into and out ofthe jaws 5 5. The holders C C each consist of a straight strip or pieceof insulating material, such as hard rubber or fiber. The blades orshanks 6 6 are secured to the ends of the holders C C, as by bendingthem over the top surfaces of the holder, as shown in Fig. 4., andfastening the-bent-over parts by screws. Each holder 0 is provided witha spring 7, secured at one end of the holder and extending lengthwise ofthe same to about the'middle thereof. The free end of each spring 7 isheld under tension by a device responsive to unduly strong currentssuch,forinstance,'as the fusible or softenable button 8. This fusible buttoncontains a coil of fine or high-resistance wire, Whose ends extend andare connected to the blades or shanks 6 6, as by the screws 9 9. Theholder C is provided with an aperture into which the top portion of thefusible button 8 can fit and through which a hook 10 can extend. Thehook 10 has its upper end engaged with the free end of the spring 7. Theholder C thus acts both as a support for the spring 7 and as means forholding the fusible-button 8 against the tension of the spring.

It will be understood thatthe line is connected'to the contact-v screws4 4 and the instrument to the contact-screws at 4 and the latter withthe spring-jaws, so that the finewire heat-coils of the fusible buttons8 8 are respectively connected in opposite sides of the circuit. Q

In the operation and use of thedevice the fusible or softenable buttonswill normally hold the springs 7 7 against their tendency to springupward, and the circuit will be complete or closed through suchheat-coils. When a sneak or an unduly strong current intrudes upon thelines, however, the heat which is generated in the fine-wire heat-coilwill operate to fuse or soften one or both of the buttons 8 8, whichwill thereupon release the corresponding spring or springs 7 7, andthese in operating will tear the fine-wire coil from the'button andsever or break it, thereby opening or breaking one or both sides of thecircuit, according as one or both of the buttons are operated.

Certain of the broader features of this construction of device forprotecting against unduly strong currents are shown, described, andclaimed in Patent No. 445,217, of Janu ary 27, 189 1, to Albert Barrett,the construction herein shown being intended principally as animprovement in specific arrangement and construction of the spring andresponsive device normally holding the spring under tension. In regardto the difference between the construction of this application and thatof the said Barrett patent it will be observed that in my arrangementthe holder 0 itself acts as a holder for the fusible button 8, as wellas a holder or support for the spring 7, whereas in the Barrett patent aseparate holder for the heat-coil is employed and secured to the holderfor the spring. It will be further noticed that in the form of myarrangement illustrated in the drawings the spring is arranged on oneside of the holder 0 and the fusible button 8 on the other side thereofand that the spring and button are connected by a hook 10 or likeconnection extending through a hole in the holder smaller than thefusible button.

The portion of the device for protecting against lightning consists of aground-electrode D and two line-electrodes E E for the opposite sides ofthe line. The form of ground-electrode shown consists of avertically-arranged iron plate or strip having a lateral flange, bywhich it is secured to the base portion 2. The line-electrodes E E areillustrated. as cylindrical carbon blocks, and these are arranged sothat their end surfaces are in position opposite and close to the upperportion of the ground-electrode D. All of the electrodes D and E arecoated with an adhesive insulating substance, in accordance with theinvention of my application, Serial No. 723,754,;filed January 13, 1899,for lightning-arrester. As a specific arrangement and matter ofimprovement over the invention'of.saidapplication I first coat thecarbons with shellac and while this is still in a liquid stateisprinkleupon it finely-powdered glass.

The line-carbons E E are respectively carried by springs 12 12, whichtend to swing upward and hold the carbons in a position away from theground-electrode D, as shown in Figs. 1, 2, and 3. The springs 12 12 areheld under tension, so as to keep the carbons E E in proximity to theground-electrode D,

by small pegs or pins 14 14, inserted in the ends of the carbons E E andarranged to extend through apertures in the ground-electrode D. Thesepins 14 are made of hard rubber or like slowly-softenable insulatingmaterial. The action of the lightning-arrester is that lightning underordinary circumstances may discharge between one of the electrodes E andthe electrode D without changing or interfering with the condition ofthe device;' but should the discharge become ofgconsiderable volume, aswhen augmented by a trolley-current, so as to form a continuone andinjurious arc, the pin 14 will be softened to such an extent that thespring will break it, whereupon the spring will be released and will flyupwardly, therebyfseparating the-line-electrode. E widely from theground-electrode D. This forms such a wide gap between electrodes thatthe lightning can no longer j ump across this space,and all futuretrouble is avoided. I

In place of the pins 14 14 any suitable de vice holding the carbons E Ein proximity to the ground-electrode D and responsive to an arc acrossthe space between said carbons, so as to release the springs, can beemployed.

The ground-electrode D is of course under stood to be connected toground, as by a wire extending from the contact or binding post 15, andthe line-carbons E E are understood to be connected with the oppositesides of. the line, a simple arrangement being to secure the springs 1212 to metallic blocks or pieces 16 16 and to connect the latter with theadjacent spring-jacks 5 d by metallic strips 1717.

From the foregoing it will be seen that the device not only affordsprotection against sneak and unduly strong currents, but also againstlightning, and also that the ground connection for the lightning will beentirely separated or opened when the discharge to groundbecomes-sufficiently great in volume to form an are. This latterfeature, it should be understood, Iconsider now in its broad conception,as well as in the specific construc tion herein set forth for carryingthat concep tion into efiect. V

The instrument thus embodying a heat-responsive device forsneak-currents in combi= nation with a lighting-arrester provided withmeans for rendering it inoperative upon the passage of an are not onlyprovides for the opening of the line upon the intrusion of a sneakorunduly strong current upon it, but also protects against the backingup of that current upon the lightning -arrester, and thereby doingdamage there and upon the ground-circuit.

It will be understood that either one of the separate features hereinset forth can be used alone as well, as in combination, as hereindescribed. 7

What I claim as my invention is- 1. The combination of a spring carryingan electrode at its free end, a fixed electrode, and a pin of softenablematerial engaging said electrodes and holding the spring against action,substantially as described.

- 2. The combination of a spring 12 having a graphite electrode E at itsfree end, a pin of softenable material projecting from said tit)electrode, and a second electrode D having coated with shellac, and alsowith a finely an aperture adapted to receive the pin in the ground orpowdered insulator, such as glass. 10

electrode E, substantially as described. In witness whereof I hereuntosubscribe my 3. In a lightningarrester, an electrode name this 19th dayof May, A. D. 1900. 5 coated with an adhesiveinsnlating substanceCHARLES A. ROLFE.

and small particles of insulating material, Witnesses: I substantiallyas set forth. A. MILLER BELEIELD,

4. In a lightning-arrester, an electrode HARVEY L. HANSON.

